Windows Server 2008 System Requirements

To use Windows Server 2008, you need:*

Component	Requirement
Processor	Minimum: 1 GHz (x86 processor) or 1.4 GHz (x64 processor) Recommended: 2 GHz or faster Note: An Intel Itanium 2 processor is required for Windows Server 2008 for Itanium-Based Systems
Memory	Minimum: 512 MB RAM Recommended: 2 GB RAM or greater Optimal: 2 GB RAM (Full installation) or 1 GB RAM (Server Core installation) or more Maximum (32-bit systems): 4 GB (Standard) or 64 GB (Enterprise and Datacenter) Maximum (64-bit systems): 32 GB (Standard) or 2 TB (Enterprise, Datacenter, and Itanium-Based Systems)
Available Disk Space	Minimum: 10 GB Recommended: 40 GB or greater Note: Computers with more than 16 GB of RAM will require more disk space for paging, hibernation, and dump files
Drive	DVD-ROM drive
Display	Super VGA (800 × 600) or higher resolution monitor
Other	Keyboard and Microsoft Mouse or compatible pointing device

*
Actual requirements will vary based on your system configuration, and
the applications and features you choose to install. Processor
performance is dependent upon not only the clock frequency of the
processor, but the number of cores and the size of the processor cache.
Disk space requirements for the system partition are approximate.
Itanium-based and x64-based operating systems will vary from these disk
size estimates. Additional available hard disk space may be required if
you are installing over a network.

Installation and Activation

Evaluating
Windows Server 2008 software does not require product activation or
entering a product key. Any edition of Windows Server 2008 may be
installed without activation and evaluated for an initial 60 days.

If
you need more time to evaluate Windows Server 2008, the 60 day
evaluation period may be reset (or re-armed) three times, extending the
original 60 day evaluation period by up to 180 days for a total
possible evaluation time of 240 days. After this time, you will need to
uninstall the software or upgrade to a fully-licensed version of
Windows Server 2008.

If you wish to extend the initial evaluation and testing period, please go here and follow the instructions.

Note:
If you are evaluating and testing Windows Server 2008 and plan to
install the software on your primary machine, it is recommended that
you back up your existing data prior to installation.

Can my existing servers run Windows Server 2008?

Download the Microsoft Assessment and Planning tool to securely inventory your existing servers and generate a migration report for Windows Server 2008.